Answer:
When high energy electron is passed through electron transport chain, it looses some of its energy.
The complexes associated with the electron transport chain uses some of this energy to pump protons (H⁺) from the matrix towards inter-membrane space.
It leads to the formation of concentration gradient across the inner membrane of mitochondria.
This gradient is used by ATP synthase (located in the inner mitochondrial membrane) for the production of ATP (adenosine triphosphate) with the help of chemiosmosis.
